1. Field of the Invention
The present invention relates to a steering column apparatus for a vehicle, and more particularly to a steering column apparatus for a vehicle having a telescopic mechanism.
2. Background Art
A telescopic mechanism for a steering column is a mechanism for adjusting the position of a steering wheel in the fore-and-aft direction to an easiest-driving position so as to adapt to the physical constitution and a preference of a driver.
The telescopic mechanism includes a clamping/unclamping mechanism operated when the driver adjusts the position of a steering wheel in the fore-and-aft direction (i.e., along the axis of the steering column). During the adjustment, the clamping/unclamping mechanism is temporarily unclamped, its position is adjusted in the fore-and-aft direction under the unclamped state, and the mechanism is subsequently returned to the clamped state.
Such a clamping/unclamping mechanism is disclosed in GB-2281375A, in which a steering column provided with a single control lever which can be operated without the driver releasing a hand from the steering wheel.
In the steering column of the cited British publication, a clamping/unclamping section of the telescopic mechanism has employed a method where a single clamping member is pressed onto a telescopic pipe so as to effect clamping. Therefore, even when a column head—which is heavy because it includes a steering wheel or an inflator for an air bag—is clamped by means of a single clamping member, the column head can be easily moved while the clamping point is used as a pivot. Further, even when the clamping force is increased, looseness is inevitably generated when the clamping section is subjected to vibrations or the like, because the clamping section has insufficient rigidity.